The performance of typical Internet applications-like transfer connect protocol (TCP) and voice over Internet protocol (VoIP) suffers from unreliable wireless communications. It has been shown that one can achieve significant performance gains by improving the communication reliability at the physical (PHY) and link layer.
Automatic Repeat reQuest (ARQ) is a widely used media access control (MAC) layer protocol that ensures end-to-end communication reliability. Typical implementations include designs such as Stop-and-Wait and Go-Back-N ARQs.
ARQ is particularly useful in wireless networks, where unreliable wireless channels can often cause packet transmission errors. Some errors or packet loss, if uncorrected and passed to the upper transport layer, will lead to very poor end-to-end performance, for popular transport protocols such TCP. For example in mobile WiMAX systems (based on the IEEE802.16e standard), a sliding window based ARQ protocol is defined at the MAC layer to:                Ensure reliable packet delivery;        Enable optional in-order packet delivery; and        Protect against any physical layer (PHY) feedback error.        
In the next generation broadband wireless networks, relay networks are a promising solution to enhance cell coverage and network capacity. Although the benefits are significant, relay networks pose new challenges in the network protocol design. For ARQ, the important question is whether ARQ should be implemented as an end-to-end (E2E) protocol or a hop-by-hop (HbH) protocol.
The present invention poses a solution to the problems set forth above and an answer to this question.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.